What is the initial approach to diagnosing and treating a urinary tract infection (UTI) in a male adult patient?

Differential Diagnosis for UTI in Adult Male Patients

When evaluating an adult male with suspected UTI, the differential diagnosis must systematically exclude urethritis, prostatitis, epididymitis, and structural urologic abnormalities, as all UTIs in males are classified as complicated infections requiring broader diagnostic consideration than simple cystitis. 1, 2

Primary Differential Considerations

Infectious Etiologies

Acute Bacterial Prostatitis

• Presents with dysuria, frequency, urgency, plus fever, chills, perineal/suprapubic pain, and obstructive voiding symptoms 2, 3
• Cannot be reliably excluded in most febrile male UTIs at initial presentation, which is why 14-day treatment courses are mandatory 2, 3
• Digital rectal examination reveals a tender, boggy, warm prostate (though DRE should be performed gently to avoid bacteremia) 1
• Requires same antimicrobial coverage as complicated UTI but minimum 14 days, potentially extending to 4 weeks for chronic bacterial prostatitis 2, 3

Urethritis (Sexually Transmitted)

• Younger men (<35 years) with dysuria should be evaluated for Chlamydia trachomatis and Neisseria gonorrhoeae 4
• Characterized by urethral discharge, dysuria without frequency/urgency, and recent sexual exposure 4
• Pyuria present but urine culture typically negative or low colony counts 4
• Requires nucleic acid amplification testing (NAAT) on first-void urine, not standard urine culture 4

Epididymitis

• Unilateral testicular/scrotal pain and swelling with or without dysuria 4
• In men <35 years, usually sexually transmitted (C. trachomatis, N. gonorrhoeae) 4
• In men >35 years, typically coliform bacteria from bladder outlet obstruction 4
• Physical examination shows tender, swollen epididymis with positive Prehn's sign 4

Pyelonephritis

• Fever, chills, flank pain, costovertebral angle tenderness with or without lower urinary symptoms 2, 3
• Represents upper tract involvement requiring parenteral therapy initially 2, 3
• Urine culture mandatory before treatment initiation 2, 3

Structural/Obstructive Causes

Benign Prostatic Hyperplasia (BPH) with Secondary Infection

• Men >50 years with chronic lower urinary tract symptoms (hesitancy, weak stream, incomplete emptying, nocturia) 1
• Urinary stasis from bladder outlet obstruction predisposes to bacterial colonization 4
• Digital rectal examination reveals symmetrically enlarged, firm prostate 1
• Post-void residual measurement indicated to assess degree of obstruction 1

Urolithiasis

• Acute onset severe flank or suprapubic pain, often colicky, with hematuria 4
• May present with secondary infection if stone causes obstruction 4
• Requires imaging (CT without contrast is gold standard) to identify stone location and hydronephrosis 4

Bladder Outlet Obstruction (Non-BPH)

• Urethral stricture, bladder neck contracture, or neurogenic bladder 1
• History of prior instrumentation, catheterization, or pelvic radiation 1
• Palpable bladder on physical examination suggests significant retention 1

Non-Infectious Inflammatory Conditions

Chronic Prostatitis/Chronic Pelvic Pain Syndrome

• Chronic pelvic/perineal pain, dysuria, voiding symptoms without documented infection 2
• Urine cultures persistently negative or show contamination only 2
• Diagnosis of exclusion after ruling out bacterial causes 2

Interstitial Cystitis/Bladder Pain Syndrome

• Chronic suprapubic pain, pressure, frequency, urgency without infection 1
• Symptoms present >6 weeks, negative urine cultures 1
• More common in women but can occur in men 1

Malignancy

Genitourinary Malignancy

• Bladder cancer, prostate cancer, or renal cell carcinoma presenting with hematuria and irritative voiding symptoms 1, 4
• Suspicious findings on DRE (hard, irregular, nodular prostate) warrant PSA testing and urology referral 1
• Persistent hematuria after treatment of presumed UTI requires cystoscopy 1

Essential Diagnostic Approach

Mandatory Initial Testing

• Urinalysis with microscopy: Assess for pyuria, bacteriuria, hematuria, and casts 1
• Urine culture with susceptibility testing: Required in ALL male patients before initiating antibiotics due to higher resistance rates and broader microbial spectrum (E. coli, Proteus, Klebsiella, Pseudomonas, Enterococcus) 2, 3, 5
• Digital rectal examination: Evaluate prostate size, consistency, tenderness, and nodularity 1
• Post-void residual measurement: If obstructive symptoms present or palpable bladder 1

Additional Testing Based on Clinical Presentation

• STI testing (NAAT): Men <35 years with dysuria and urethral discharge 4
• Serum PSA: Men >50 years with abnormal DRE findings or when life expectancy >10 years and prostate cancer diagnosis would change management 1
• Renal function tests: Suspected pyelonephritis or obstruction 2
• Blood cultures: Fever, chills, or signs of sepsis 2
• Imaging (CT or ultrasound): Suspected obstruction, stones, abscess, or treatment failure 2, 3

Critical Diagnostic Pitfalls to Avoid

Do not treat empirically without urine culture in males - The microbial spectrum is broader and resistance rates higher than in uncomplicated female cystitis, making culture-guided therapy essential 2, 3, 5

Do not assume simple cystitis - All male UTIs are complicated by definition and require 14-day treatment courses because prostatitis cannot be excluded at initial presentation 2, 3

Do not miss sexually transmitted urethritis - In younger men with dysuria but minimal frequency/urgency and urethral discharge, obtain NAAT testing rather than relying solely on urine culture 4

Do not overlook obstruction - Assess for bladder distention, perform post-void residual, and consider imaging if recurrent infections or treatment failure occurs 1

Do not use nitrofurantoin or fosfomycin for febrile UTIs - These agents do not achieve adequate tissue concentrations for pyelonephritis or prostatitis 2